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(NVOMOdeL) L. H. LATIMER.

PROCESS 0F MANUFACTURING CARBONS.

Patented Jan. 17,1882.

No.l 252,386.

'f iV// Fig.' 3

UNITED STATES PATENT. OFFICE.

LEWIS H. LATIMER, OF NEW YORK, N. Y., ASSIGNOR TO THE UNITED STATESELECTRIC LIGHTING COMPANY, OF SAME PLACE.

PROCESS'OF MANUFACTURING CARBONS.

SPECIFICATION forming' part of Letters Patent No. 252,386, dated January17, 1882.',

Application tiled February 19, 1881. (No model.)

To all whom it may concern:

Be it known that I, LEWIS H. LATIMER, of New York, in the county of NewYork and State of New York, have invented certain new and usefulImprovements in the Manufacture of Carbons for Electric Lamps, of whichthe following is a specification, reference being had to the drawingsaccompanying and forming a part thereof.

1o My invention relates more particularly to carbonizing the conductorsfor incandescent lamps, though it is equally applicable to themanufacture of delicate sheets or strips of dense and tough carbondesigned for any purpose whatever; and it consists in carbonizing blanksand forms of textile, fibrous, or other carbonizable material inprotecting-envelopes of a material whose rate of contraction, whenexposed to a high temperature and under conzo ditions which preclude theadmission of air, is

the same, or approximately the same, as their own.

In the methods ofcarbonizing employed previous to my invent-ion theblanks cut from fibrous or textile materials were confined in grooves orlaid between plates of metal or carbon and charred inasutableclosedinutile. To prevent the strips from adhering to the plates they werecoated with graphite or laid between 3o strips of thin tissue-paper. When heated the confining-plates expand, while the blinks between themcontract very considerably under the intense heat of the furnace, sothat many ofthem are broken and distortedin consequence of theirextremely-delicate structure and their tendency to shift their positionbetween the plates. This I avoid by the method I propose, and which isillustrated in the accompanying drawings, in which- Figure 1 illustratesthe method of inclosing the blanks in the protective envelopes; Fig. 2,sectional view of the earbonizer, and Fig 3 a plan -view of a portion ofthe cover for use therewith.

The blanks a, of fibrous material, usually such as paper, strips ofwood, or the like, are inclosed in small envelopes composed of sheetsot' card-board b c, which are sufiiciently strong to prevent cracking orcrumbling when carbon- 5o ized.

The blanks are prevented from sticking to the envelopes by coating themor the inner faces ot' the envelopes with graphite, lampblack, orsimilar non-adhesive substance,or by interposing between the two stripsof tiss'ue- 55 paper.

A is a retort or mue for carbonizing the blanks. It is composed of a boxof refractory material with handle B and a corrugated bottom, C, uponwhich is placed a block or plate, 6o F, of fire-clay, metal, or otherrefractory material. Upon this plate F are spread a. number of theenvelopesH, inclosing the blanks to be carbonized. Over these anotherplate, ofsimilar character, is laid, then other enveloped blanks andplates until the box is' nearly full. The whole is covered by aperforated plate, D, on which is placed a layer of sand, some raw cottonbeing spread over the perforations E in the cover to prevent the sandfrom filtering 7o through into the carbonizer. This also prevents theaccess of air into the box, while allowing the gas driven off by theheat to escape. The plat-es F are somewhat smaller than the interiorofthe boxfA, so that the gases which are driven 'off by the heat, orwhich may be introduced in the process of carbonization, have freepassage for their escape, as shown by the arrows in Fig.2. The weightofthe superposed cover and sand exerts a continuouspressure on 8o thelayers ot' blanks between the plates, thus lessening their tendency tobuckle or warp, and confining their only injurious movement to ahorizontal contraction. By the use ofthe paper sheets or envelopesinclosing the delicate blanks, the latter are protected from attritionwith the plates when the latter are expanded by the heat.

The sheets b c must be of reasonably stout cardboard, or of a substanceof such tenacity 9c of liber that it will not easily crack or break whencarbonized.

I would also state that instead of an envelope for each blank severalblanks may be inclosed in each envelope; but the arrangement shown isthe one preferred by me, as in practice I have found it the mostpracticable and productive of the best results.

I am aware that blanks of the kind described have been carbonized in aclosed muide or tlask roo and between plates of iron, carbon, or otherrefractory material. I am also aware that for preventing the blanks fromadhering to the said plates, strips ot' tissue-paper have been laidbetween them, and this I have described in conjtuiction'nith my presentinvention, but do not desire to lay claim herein to the same, broadly;but, v

Having now described my invention, what I claim is- 1. The process ofearbonizing shapes or blanks of carbonizable material, substantially asdescribed, which consists in subjecting the same to a high temperaturewhile inclosed in envelopes or between sheets of card-board orequivalent material whose rate of expansion L. H. LATIMER.

Witnesses:

EDWARD P. ROBERTS, JOSEPH V. NICHOLS.

